Add unit tests to analytics service

Description

Add src/test unit tests for all services and repositories in the analytics microservice. Tests use mocked dependencies — no external infrastructure (ClickHouse, Docker) required to run them.

This slice depends on #35050 being complete so tests are written on clean, stable code.

Parent epic: #35048

Acceptance Criteria

• Unit tests added for all public methods in all service classes
• Unit tests added for all public methods in all repository classes
• All dependencies mocked (no real ClickHouse or network calls)
• Tests run with ./mvnw test — no external infrastructure needed
• All tests pass on

Additional Context

• Source task: Task 3 (Unit tests) from the improvement plan
• Blocked by: #35050 (ingest code refactor must be done first)
• Framework: JUnit 5 + Mockito (standard for this project)
• Related branch: issue-34849-Add-dotCMS-Analytics-Proxy-Endpoint-for-/v1/analytics/-to-dot-ca-event-manager

Start in the analytics microservice's src/test directory and inspect the service and repository classes whose public methods need coverage. Use JUnit 5 and Mockito, with all dependencies mocked, and run ./mvnw test. Done means every public service and repository method has passing unit tests without ClickHouse, Docker, network calls, or other external infrastructure.